A first node determines a second node belonging to the same first group as the first node, and creates a first receive buffer corresponding to the second node in a memory. The first node determines a third and a fourth node belonging to a second group, and creates a second receive buffer corresponding to the third node in the memory, without creating a receive buffer corresponding to the fourth node. The first node uses the first receive buffer to receive messages when communicating with the second node, uses the second receive buffer to receive messages when communicating with the third node, and uses the first receive buffer or the second receive buffer to receive messages when communicating with the fourth node.